- Email: [email protected]
39 Modulation of neurite growth by interactions of neural cell adhesion molecules with brain proteoglycans
37
38
GUIDANCE BY AXON DIFFUSIBLE ATTRACTANTS AND REPELLENTS
GLIAL
Tlto Serafini,* Sophia .4. Colarmarino.7 Michael I. Ga1ko.t Timothy E. Kennedy) E David Leonardo.7 Chnstmc Slirzayan,t Josf R. de la Torre.7 Ilao Wang,t Rosa S. [email protected] Thomas M. Jessell,§’ Wilham C ~karnes.0 and MarcTessrer-Iavignct*Umverslty of Califorma. Berkeley; tlJnivers!r) of C&forma. San Francisco; kational iostltute for MedIcal Research, London; &olumbia Umverslty; “Howard Hughes Medical Institute, *University of E&burgh CommissuraJ sons pioneer a clrcumferenbal pathway to the floor plate at the venual midline of the spinal cord. Floor plate cells secrete a diffusible factor that attracts these axons tn VIITO. suggesting that then ventral growth IS directed by cbemotropism We have purified from embryomc chick bram two proteins. netnn -I and netrin-2. that each mimic the activity of the iloor plate Cloning of cDNAs encoding the netnns shows lhat they are vertebrate bomologues of UNC-6, a lamlmn-related protein required for the circumferenbal dorsal and ventral rmgration of cells and i~xons in the nematode C. elegant. The netnn- I gene 1s expressed by floor plate cells, and beterologous cells secreung recombinant netrin- 1 munic the long-range cbemotropic activity of floor plate cells Moreover, axons that grow dorsally away from the floor plate are repelled by netrin-1. Thus. nelnn-1 is a bifunctional guidance cue that may serve to attract some axons LO the floor plate while steering others away Enamma(lon of the trajectories of conunissural axons in race lackmg nebin-l imhcates that netnn-1 is required in V~L’O for the growth of most commissnral axons to the floor plate. Netin- is also required 1~1~110for the proper development of other commissures such as the hppocampal c~mm~~urc and rhe corpus callosum
ECM
IN
NELJRAI.
DEVELOPMENT
AND PLASTICITY Faissner, A., A. Scholze, B. G&z, A. Joester, 0. Schngdelbach, F. Wigger, K. Schiitte, and A. Clement. Department of Neurobiology, INF 364, D-69120 Heidelberg, FRG. It has become increasingly clear that glycoproteins and proteoglycans of the extracellular matrix mediate glial influences on neural pattern formation. In this context, tenascin-C (TN-C) glycoproteins have gained increasing attention because they are transiently expressed by astrocytes during CNS development, delineate functional processing units in some areas and affect neuron migration and neurite outgrowth. We have generated a library of recombinant TN-C domains and could assign neuronal cell binding sites, neurite outgrowth stimulating and repulsive properties to distinct domains. Recently, the glial-derived chondroitin sulfate proteoglycan DSD-I-PG was purified from postnatal mouse brain with the help of mAb 473HD. DSDl-PG stimulates neurite outgrowth by El8 hippocampal neurons, a function which requires the DSD-Iepitope specifically recognized by mAb 473HD. On the basis of these observations, we propose that glial ECM-constituents could play an important role in regulating neurite sprouting and pruning during neural development and plasticity. Supported by DFG (SFB 317, Fa-159l5-1,2) und Schilling-.Stiftung)
39
40
MODULATION OF NEURITE GROWTH BY INTERACTIONS OF NEURAL CELL ADHESION MOLECULES WITH BRAIN PROTEOGLYCANS
REGULATED
EXPRESSION OF NEURONAL
pR(-JTEpJS
nrm7uc-
M. Grumet. T. Sakmai. D. Friedlander & M. L&g. NYU Medical Center, Dept. of Pharmacology. 5.50Fit Ave. NY. NY, 10016 Cell adhesion molecules (CAM), in addition to forming cell-celJ bonds, are believed to modulate cell migration and axonal growth by activating signal transduction pathways. We found that two major brain chondroitin sulfate proleoglycans (neurocan and phosphacan) bind to several neural CAMS and inhibit neurile growth promoted by Ng-CAM. Neurocan is secreted by neurons and phosphacan by glia and glial progenilors. Phosphacan is a splicing variant of a receptor protein tyrosine phosphatase called RPTF’B, lacking transmembrane and cytoplasmic phosphatase domains. Glia also express two receptor forms of RPTPD that differ in a large extracellular domain. Phosphacan is much more abundant than either of fhe receptor forms in rat brain during development. Cilia expressing RPTF’B adhered and extended processes on substrates coated with Ng-CAM. These cells secrete large amounts of phosphacan which inhibits their adhesion and process extension on Ng-CAM. In viva, RPTPB is found in certain regions thought lo be barriers 10 neurons and in developing fiber tracts through which axons project. Interestingly, amino terminal regions of RPTPD were found to promote neuronal adhesion and neurite growth. This activity was found to involve the carbonic anhydrase domain of RFTPS which acts as a ligand for contactin. Contactin is a lipid-anchored axonal CAM and we have evidence that another neuronal receptor that binds lo it is required for neurite growth inducedby RI’TPB. The results show that expression of RPTPlVphosphacan changes dramatically during development and suggest that different domains in the molecule modulate growth and differentiation of neurons and glia by interacting with several CAMS and extracellular matrix proteins.
AYrlN
SURFACE
f?DCIuFru
AnIn
REGENERATION C.A.O. Stuermer, U. Laessing, S. Giordano, H. Ott, T. Schulte, and M. Bastmeyer. Faculty of Biology, University of Konstanz, D78434 Konstanz, Germany We have identified severalsurfaceproteinsin the fish central nervous system (CNS), which are. expressedduring neuronal differentiation and axon growth in the embryo (E 587 antigen, neurolin) and in newly added ganglion cells (RGCs) in the continuouslygrowing retina of adult fish @ 587 Ag, neurolin, reggie). E 587 Ag and neurolin belong to the Ig superfamily of cell adhesion molecules. Reggie represents a new family of surface proteins of which two cDNAs, reggie-1 and reggie-2 were identified. All proteins are re-expressed by all RGCs after optic nerve lesion and during RGC axon regeneration, but the onset, durationand localization of re-expression is protein specific. The expression patterns indicate that these proteins subserve fimctions during CNS development and fiber tract repair. Aspects of their function were explored by in viva and m vrtTo experiments using the relevant antibodies, and these results will bc presented.
38
GUIDANCE BY AXON DIFFUSIBLE ATTRACTANTS AND REPELLENTS
GLIAL
Tlto Serafini,* Sophia .4. Colarmarino.7 Michael I. Ga1ko.t Timothy E. Kennedy) E David Leonardo.7 Chnstmc Slirzayan,t Josf R. de la Torre.7 Ilao Wang,t Rosa S. [email protected] Thomas M. Jessell,§’ Wilham C ~karnes.0 and MarcTessrer-Iavignct*Umverslty of Califorma. Berkeley; tlJnivers!r) of C&forma. San Francisco; kational iostltute for MedIcal Research, London; &olumbia Umverslty; “Howard Hughes Medical Institute, *University of E&burgh CommissuraJ sons pioneer a clrcumferenbal pathway to the floor plate at the venual midline of the spinal cord. Floor plate cells secrete a diffusible factor that attracts these axons tn VIITO. suggesting that then ventral growth IS directed by cbemotropism We have purified from embryomc chick bram two proteins. netnn -I and netrin-2. that each mimic the activity of the iloor plate Cloning of cDNAs encoding the netnns shows lhat they are vertebrate bomologues of UNC-6, a lamlmn-related protein required for the circumferenbal dorsal and ventral rmgration of cells and i~xons in the nematode C. elegant. The netnn- I gene 1s expressed by floor plate cells, and beterologous cells secreung recombinant netrin- 1 munic the long-range cbemotropic activity of floor plate cells Moreover, axons that grow dorsally away from the floor plate are repelled by netrin-1. Thus. nelnn-1 is a bifunctional guidance cue that may serve to attract some axons LO the floor plate while steering others away Enamma(lon of the trajectories of conunissural axons in race lackmg nebin-l imhcates that netnn-1 is required in V~L’O for the growth of most commissnral axons to the floor plate. Netin- is also required 1~1~110for the proper development of other commissures such as the hppocampal c~mm~~urc and rhe corpus callosum
ECM
IN
NELJRAI.
DEVELOPMENT
AND PLASTICITY Faissner, A., A. Scholze, B. G&z, A. Joester, 0. Schngdelbach, F. Wigger, K. Schiitte, and A. Clement. Department of Neurobiology, INF 364, D-69120 Heidelberg, FRG. It has become increasingly clear that glycoproteins and proteoglycans of the extracellular matrix mediate glial influences on neural pattern formation. In this context, tenascin-C (TN-C) glycoproteins have gained increasing attention because they are transiently expressed by astrocytes during CNS development, delineate functional processing units in some areas and affect neuron migration and neurite outgrowth. We have generated a library of recombinant TN-C domains and could assign neuronal cell binding sites, neurite outgrowth stimulating and repulsive properties to distinct domains. Recently, the glial-derived chondroitin sulfate proteoglycan DSD-I-PG was purified from postnatal mouse brain with the help of mAb 473HD. DSDl-PG stimulates neurite outgrowth by El8 hippocampal neurons, a function which requires the DSD-Iepitope specifically recognized by mAb 473HD. On the basis of these observations, we propose that glial ECM-constituents could play an important role in regulating neurite sprouting and pruning during neural development and plasticity. Supported by DFG (SFB 317, Fa-159l5-1,2) und Schilling-.Stiftung)
39
40
MODULATION OF NEURITE GROWTH BY INTERACTIONS OF NEURAL CELL ADHESION MOLECULES WITH BRAIN PROTEOGLYCANS
REGULATED
EXPRESSION OF NEURONAL
pR(-JTEpJS
nrm7uc-
M. Grumet. T. Sakmai. D. Friedlander & M. L&g. NYU Medical Center, Dept. of Pharmacology. 5.50Fit Ave. NY. NY, 10016 Cell adhesion molecules (CAM), in addition to forming cell-celJ bonds, are believed to modulate cell migration and axonal growth by activating signal transduction pathways. We found that two major brain chondroitin sulfate proleoglycans (neurocan and phosphacan) bind to several neural CAMS and inhibit neurile growth promoted by Ng-CAM. Neurocan is secreted by neurons and phosphacan by glia and glial progenilors. Phosphacan is a splicing variant of a receptor protein tyrosine phosphatase called RPTF’B, lacking transmembrane and cytoplasmic phosphatase domains. Glia also express two receptor forms of RPTPD that differ in a large extracellular domain. Phosphacan is much more abundant than either of fhe receptor forms in rat brain during development. Cilia expressing RPTF’B adhered and extended processes on substrates coated with Ng-CAM. These cells secrete large amounts of phosphacan which inhibits their adhesion and process extension on Ng-CAM. In viva, RPTPB is found in certain regions thought lo be barriers 10 neurons and in developing fiber tracts through which axons project. Interestingly, amino terminal regions of RPTPD were found to promote neuronal adhesion and neurite growth. This activity was found to involve the carbonic anhydrase domain of RFTPS which acts as a ligand for contactin. Contactin is a lipid-anchored axonal CAM and we have evidence that another neuronal receptor that binds lo it is required for neurite growth inducedby RI’TPB. The results show that expression of RPTPlVphosphacan changes dramatically during development and suggest that different domains in the molecule modulate growth and differentiation of neurons and glia by interacting with several CAMS and extracellular matrix proteins.
AYrlN
SURFACE
f?DCIuFru
AnIn
REGENERATION C.A.O. Stuermer, U. Laessing, S. Giordano, H. Ott, T. Schulte, and M. Bastmeyer. Faculty of Biology, University of Konstanz, D78434 Konstanz, Germany We have identified severalsurfaceproteinsin the fish central nervous system (CNS), which are. expressedduring neuronal differentiation and axon growth in the embryo (E 587 antigen, neurolin) and in newly added ganglion cells (RGCs) in the continuouslygrowing retina of adult fish @ 587 Ag, neurolin, reggie). E 587 Ag and neurolin belong to the Ig superfamily of cell adhesion molecules. Reggie represents a new family of surface proteins of which two cDNAs, reggie-1 and reggie-2 were identified. All proteins are re-expressed by all RGCs after optic nerve lesion and during RGC axon regeneration, but the onset, durationand localization of re-expression is protein specific. The expression patterns indicate that these proteins subserve fimctions during CNS development and fiber tract repair. Aspects of their function were explored by in viva and m vrtTo experiments using the relevant antibodies, and these results will bc presented.